Gate drive assembly

ABSTRACT

A drive, preferably a gate drive with a belt transmission encompassing a drive pulley and an output pulley. According to the invention the drive pulley consists of at least one cylinder with inwardly tapering flanges at its ends. A round belt, rope or similar serves as a drive agent, which is wound a number of times around the cylinder. The return strand of the round belt, rope or similar can be held continuously under tension.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention refers to a drive, preferably a gate drive, with a belttransmission comprising of a drive pulley and an output pulley.

2. Description of the Related Art

Such belt transmissions as gate drives are familiar from the prior artas toothed belt transmissions. A motor-driven cog drives a correspondingtoothed belt which is led over an idler pulley at the other endconsisting of a cog wheel. Due to the size of the individual teeth ofthe toothed belt and of the corresponding cog, a certain minimumdiameter must be maintained in the design of the drive pulley so thatthe whole drive unit is rather large. As well as this, the toothed beltsused are relatively expensive.

A cheaper version consists in the use of roller chains led overcorresponding cog wheels. Although roller chains are capable oftransmitting very high forces, they cause unacceptable noise emissionsin operation. In addition to this, the cog wheels used here also have tohave a certain minimum diameter which means that the overall unit isrelatively large.

Thus, the task of the present invention is to create a gate drive which,on the one hand can be realised cost-effectively and, on the other hand,can transmit large forces in a compact size.

SUMMARY OF THE INVENTION

In the invention, this task is solved by a drive, preferably a gatedrive with a belt transmission having a drive pulley and an outputpulley. Accordingly, a drive pulley is formed from at least one cylinderwhich has flanges tapering inwards at its ends. As a drive element around belt, rope or similar is wound a number of times around thecylinder. The return strand of the round belt, rope or similar can beheld continuously under tension.

In the design of the drive according to the invention the same principleis applied as in electrically driven idler pulleys used particularly inshipping. The corresponding belt is wound around this electricallydriven idler pulley a number of times. The belt slips through while theelectrically driven idler pulley is rotating until the end of the returnstrand is subjected to tension. Due to the tension on the return stranda frictional grip is generated between the belt and the electricallydriven idler pulley. The force that can be taken up by such a contacttransmission with the load strand is expressed after Eytelwein by thefollowing equation:

F₁=F₂·e_(μα)

where F₁, is the force acting on the load strand, F₂ the force acting onthe return strand, μ the coefficient of friction and α the wrap inradian measure.

Up to now there was no simple way of transferring this contacttransmission familiar from shipping to a garage gate drive, as in agarage gate drive the reversal of the direction of rotation meant thatthe load switched between the return strand and the load strand, wherebythe belt is forced to slip on the drive pulley when the load isreversed. Due to the design of the drive according to the invention itis now ensured that the round belt, rope or similar serving as the driveelement always remains in frictional contact with the drive pulley evenwhen the direction of rotation changes.

In a first preferred version of the invention, the drive pulley consistsof two cylinders with flanges tapering inwards on their respective ends,whereby the round belt, rope or similar is wrapped a number of timesaround each cylinder and whereby the end respectively forming the returnstrand is led around a spring-loaded idler pulley. This design meansthat the necessary tension is exercised in a simple manner on the returnstrand. In this, the idler pulley around which the respective returnstrand is led, can be arranged between the respective ends of the roundbelt, rope or similar which respectively form the load strand.Alternatively, the idler pulley may also be arranged outside of the endsof the round belt, rope or similar forming the load strand. The springsexercising the spring force may be realised either as tension orcompression springs.

Another alternative version of the drive according to the inventionentails the drive pulley consisting of only one cylinder with flangestapering inwards at its ends. Here the two ends of the round belt, ropeor similar are also led over fixed idler elements, between which twoidler pulleys are arranged on a moveable carriage arranged perpendicularto the direction of the round belt, rope or similar, around which theround belt, rope or similar is also led. The distance between thepulleys arranged on the carriage is smaller than that between the idlerelements opposite each other. In this version when the load strand istightened it is drawn through on the load side for the most partstraight between the rigid idler elements and the idler pulley. Thecross-sliding carriage is drawn across to the side to the load strand.The load strand which runs mainly straight along the idler elements andthe idler pulley has only a minor contact with the fixed idler elementsso that only a negligible frictional force is exercised. The idlerelement on the return strand of the carriage is drawn inwards by slidingthe carriage to the load strand side thereby taking the return strandwith it so that the angle of wrap of the return strand around the fixedidler elements on the return strand is enlarged. This generates arelatively large frictional force which is sufficient to generate therequired frictional contact between the belt and the drive pulley.

A further design principle for further development of the driveaccording to the invention consists in the fact that the tension on thereturn strand is generated by two staggered tensioning elements whichwork on the principle of a bicycle chain adjuster.

It is an advantage when, at the end of the round belt, rope or similarrespectively forming the load strand, there is fixed a carriage with anarticulation point, for example for a sectional gate, which can slideback and forth.

It is especially advantageous when an additional tension spring isintegrated in the load strand. With this version, a torsion spring,required in the prior art and integrated on the usual spring shaft toroll up the sectional gate, can be replaced. Instead of the usualtake-up pulley on which the belt would also be wound up here, in thiscase the design with the diameter of the correspondingly motor-drivenpulley can be retained. With this design the large-diameter take-uppulley as was required in the prior art can be replaced. As well asthis, the relatively expensive torsion spring required by the prior artcan be replaced by a low-cost linear spring.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details and advantages of the invention are explained in thefollowing in conjunction with the execution examples shown in thedrawings. These are:

FIGS. 1a, b: side view and plan view of an initial basic version of thedrive according to the invention

FIGS. 2a, b: an enlarged detail view of part of FIGS. 1a, 1 b

FIGS. 3a, b: a detail view corresponding to that in FIG. 2 in a modifiedversion

FIGS. 4a, b: a version corresponding to FIGS. 2a, b of a further versionof the present invention

FIGS. 5a, b: a representation corresponding to FIGS. 2a, b of a fourthversion of the present invention and

FIG. 6: a plan view of a fifth version of the drive according to theinvention

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

FIGS. 1a and 1 b show a gate drive 10 which is integrated in a mountingrail in a manner not shown here. The drive 10 consists of a belttransmission with a drive pulley 12 and an output pulley 14 in the formof an idler pulley. An endless round belt, rope or similar 16 (rope) isled around the drive pulley 12 and the output pulley 14. The round belt,rope or similar 16 moves a carriage 18 back and forth with anarticulation point not detailed here in the directions of the doublearrows ‘a’ depending on the direction of drive (double arrows ‘M’) ofthe drive pulley 12. The carriage 18 is connected to one end of theround belt, rope or similar 16 by means of a positively interlockingelement 20 as shown in FIG. 1b.

As can be seen in FIGS. 2a and 2 b, the drive pulley 12 consists here oftwo cylinders 22 arranged alongside each other on a shaft and withinwardly tapering flanges 24 on the respective ends. The round belt,rope or similar 16 is wound four times around each cylinder 22, and theend forming the return strand 22 in each case is led around aspring-loaded idler pulley 28. In the version shown here thespring-loaded idler pulley 28 lies between the ends of the round belt,rope or similar 16 forming the load strand. In the present example thespring force is provided in the direction of the arrow ‘b’ by a tensionspring 30.

The spring force exerted on the return strand 26 through the idlerpulley 28 is sufficient to maintain the frictional contact between theround belt, rope or similar 16 and the drive pulley 12 even when thedirection of rotation changes in the directions of the double arrows‘M’.

FIGS. 3a and 3 b show a version in which the idler pulley 28′ isarranged outside of the ends of the round belt, rope or similar formingthe load strand. This allows the realisation of a relatively longer butnarrower design version. The idler pulley 28′ is also spring-loaded bytension spring 32 in the direction of the arrow ‘c’. The other partscorrespond to those of the version shown in FIG. 1a or 1 b so thatreference is made here to the description above.

The FIGS. 4a and 4 b show a version corresponding to the designaccording to FIGS. 2a, 2 b in which the idler pulley 29 is spring-loadedby a correspondingly arranged compression spring 34 in the direction ofthe arrow ‘d’. The other parts correspond to the version described aboveso that reference is made to this description.

The FIGS. 5a and 5 b show a version which corresponds for the most partwith that shown in FIGS. 3a and 3 b, whereby the spring force in thisversion is exerted in the direction of the arrow ‘e’ by a compressionspring 36. The other parts correspond to those of the previous versionand are thus marked with identical reference symbols.

A version of the present invention based on an alternative executionconcept is shown in FIG. 6. Here the drive pulley 112 motorically drivenin the directions of the double arrows ‘M’ is formed from a cylinderwhich has inwardly tapering flanges at its ends. A round belt, rope orsimilar 116 is wound four times around this cylinder. Opposite the drivepulley 112 is the output pulley 114 also formed from an idler pulley. Acarriage or carriage driver 118 can be moved back and forth by the roundbelt, rope or similar 116 in the directions of the double arrows ‘a’corresponding to the direction of rotation of the drive pulley 112. Theround belt, rope or similar 116 is led over fixed idler elements 140. Inthe version shown here the idler elements 140 are arranged in such a waythat the parallel ends of the round belt, rope or similar havetangential contact with them. Between each two opposite idler elements140 there are rotatable idler pulleys 144 arranged on a carriage 142which can be moved across in the directions of the arrows ‘f’. The roundbelt, rope or similar 116 is led around the idler pulley 144 in themanner shown in FIG. 6. The distance between the idler pulleys 144pivoted on the carriage 142 is smaller than the distance I between thefixed idler elements 140.

In FIG. 6 the round belt, rope or similar 116 runs on one side mainlystraight between the idler elements 140 and the idler pulley 144. Onthis side the round belt, rope or similar forms the load strand 128while on the opposite side the round belt, rope or similar 116 forms thereturn strand 116. The exertion of the load causes the round belt, ropeor similar 116 forming the load strand 128 to be pulled straight so thatit pushes the carriage 142 into the position shown here, therebydeflecting the return strand 126 as shown in FIG. 6 around the idlerelements 140 and the idler pulley 144 in such a way that a comparativelylarge angle of wrap results at the idler elements 140. This enlargedangle of wrap generates a sufficiently large force to ensure thefrictional contact between the round belt, rope or similar 116 and theidler pulley 112. In the case of a change in the direction of rotationin the directions of the double arrows ‘M’, a direct kinematic reversalis caused due to the directly resulting reversal of the load due to thecorresponding lateral movement of the carriage 142 in the direction ofthe arrows ‘f’, so that the load strand and the return strand can bechanged without any time interval for the transition during which thefrictional contact between the round belt, rope or similar 116 and thedrive pulley 112 can no longer be maintained.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be recognized by one skilled in the art areintended to be included within the scope of the following claims.

What is claimed is:
 1. A gate drive with a belt transmission comprisinga drive pulley and an output pulley, the drive pulley including at leastone cylinder which has inwardly tapering flanges at its ends, a roundbelt wound around the cylinder a number of times as a drive element, areturn strand of the round belt held continuously under tension, and acarriage with an articulation point which can be moved back and forth bya load strand, said carriage movement being essentially perpendicular toa direction of movement of the load strand between the drive pulley andthe output pulley.
 2. The gate drive according to claim 1, wherein thedrive pulley includes two cylinders with inwardly tapering flanges attheir respective ends, whereby the round belt is wound a number of timesaround each cylinder and whereby the return strand is led around aspring-mounted idler pulley.
 3. The gate drive according to claim 1,wherein a tension spring is integrated in the load strand.
 4. The gatedrive according to claim 1, wherein the gate drive operates to move asectional gate.
 5. The gate drive according to claim 1, wherein theround belt is a rope.
 6. The gate drive according to claim 1, whereinthe direction of movement of the carriage is essentially perpendicularto the direction of movement of the load strand between the drive pulleyand the output pulley.
 7. The gate drive according to claim 2, whereinthe spring-mounted idler pulley around which the return strand is ledlies along a part of the round belt forming the load strand.
 8. The gatedrive according to claim 2, wherein the spring-mounted idler pulleyaround which the return strand is led lies outside of a part of theround belt forming the load strand.
 9. The gate drive according to claim7, wherein the spring is a tension spring.
 10. The gate drive accordingto claim 7, wherein the spring is a compression spring.
 11. The gatedrive according to claim 7, wherein the drive pulley includes a cylinderwith inwardly tapering flanges at its axial ends, both the load strandand the return strand of the round belt being led over fixed idlerelements, between which idler pulleys are arranged on a cross-slidingcarriage around which the round belt is also led, whereby a distancebetween the pulleys arranged on the carriage is smaller than a distancebetween the fixed idler elements on the load strand of the round beltwith respect to opposing fixed idler elements on the return strand ofthe round belt.
 12. A gate drive with a belt transmission, comprising adrive pulley and an output pulley, the drive pulley including at leastone cylinder, a round belt wound around the cylinder a number of timesas a drive element, a return strand of the round belt held continuouslyunder tension, and a carriage with an articulation point which is movedback and forth by a load strand, the direction of movement of thecarriage being substantially perpendicular to the direction of movementof the load strand and the return strand between the drive pulley andthe output pulley, such that movement of the carriage causes one of theload strand and the return strand to be deflected depending on adirection of rotation of said drive pulley.
 13. The gate drive as setforth in claim 12, further comprising two fixed idler elements on a sideof the return strand and two fixed idler elements on a side of the loadstrand, said carriage having a first idler element on the side of thereturn strand and a second idler element on the side of the load strand,wherein when the load strand is tightened it is drawn throughsubstantially straight between the fixed idler elements and the secondidler element on the load strand side, said carriage sliding to the loadstrand side such that the first idler element and said return strand aredrawn inwardly, enlarging an angle of wrap of the return strand aroundthe fixed idler elements on the return strand side and increasingfrictional force.
 14. The gate drive according to claim 13, wherein adistance between the first and second idler elements is smaller than adistance between the fixed idler elements on the load strand side withrespect to opposing fixed idler elements on the return strand side.